1. Field Of The Invention
The invention relates to microgrippers which can be used with micromanipulators.
2. Background Art
Remotely controlled microgrippers in conjunction with manipulators that are used for grasping, moving and positioning a variety of objects from a remote position are known. The microgrippers and manipulators may be manually controlled or controlled by a machine, such as, modern data processing apparatus. Such microgrippers and manipulators are used, for example, in modern robot aided manufacturing and assembly procedures and in handling dangerous materials.
Russian Patent No. 1,400,877 discloses a robot gripper which has a spring-loaded slide inside of a casing and which is connected by a pivot rod of a power cylinder. In more detail, the robot gripper has a casing, to which is attached a fixed jaw and within which is located a spring acting upon a slide connected through a pivot to the rod of a power cylinder. A moving jaw is rigidly attached to the slide and the second bearing point of the moving jaw is a guide rigidly connected to the fixed jaw. The pivot prevents wedging between the slide and the rod of the cylinder, and the guide provides rigidity for the jaws.
U.S. Pat. No. 4,565,400 discloses a double hand for an industrial robot which has a hand body, two sets of work clamping units and two sets of actuators to drive the work clamping units, respectively, for opening and closing motions. The hand body has a rear end attachable to the free end of the robot wrist of an industrial robot, a front end and opposite sides which extend between the front end and the rear end. Each working clamping unit has a pair of gripping fingers, and the pairs of gripping fingers of the two sets of work gripping units are supported pivotally at the roots thereof on the opposite sides of the hand body for turning motion. The paired gripping fingers are turned about the respective roots thereof in opposite directions by the associated actuator.
U.S. Pat. No. 4,696,501 discloses an electronic force-detecting robot gripper, for gripping objects, which is attached to an external robot arm. The gripper includes motor apparatus, gripper jaws, and electrical circuits which drive the gripper motor and sense the amount of force applied by the jaws. The force applied by the jaws is proportional to a threshold value of the motor current. When the motor current exceeds the threshold value, the electrical circuits supply a feedback signal to the electrical control circuit which, in turn, stops the gripper motor.
U.S. Pat. No. 4,796,357 discloses a placement head assembly for use in an electrical component placement machine. A hollow main shaft has a carriage assembly disposed thereabouts with rollers which provide axial movement along the shaft. A vacuum support shaft within the main shaft telescopes downwards to pickup and retain a component. The carriage assembly carries actuator means which urge it into axial movement in response to fluid pressure differentials. Tweezer means are pendently disposed in quadrature from pivot points about the shaft. Pivoting action of the tweezer means forces jaws radially inwards into contact with the component, thereby aligning it for subsequent board placement. In one embodiment, the actuator means includes a piston-cylinder assembly. Pressure differential across the piston causes downward movement of the carriage assembly. Reverse pressure differential urges the carriage assembly upward.
U.S. Pat. No. 4,552,397 discloses a dolling/donning apparatus used in combination with a row of winders each of which winds filamentary material upon a tube carried by a rotary spindle of the winder to form a package. The apparatus includes a carrier mounted for movement generally parallel to and above the row of winders. A column is mounted on the carrier for horizontal movement. A package exchange arm is mounted on the column for up-and-down movement and is alignable with the winder spindle so that the package can be transferred to the package exchange arm. A tube exchange arm is mounted on the column for up-and-down movement and is alignable with the spindle so that a tube on the tube exchange arm can be transferred to the spindle. A shuttle is spaced horizontally from and vertically above the row of winders, and includes a package transfer arm and a tube transfer arm. The package exchange and tube exchange arms are moved along the column to the level of the shuttle. The column is moved horizontally toward the shuttle so that the package can be transferred from the package exchange arm to the package transfer arm, and a tube can be transferred from the tube transfer arm to the tube exchange arm. The shuttle is transferred to a remote station where the package is removed from the package transfer arm and a tube is inserted on the tube transfer arm. The tube exchange arm has a rotary cylinder which has inwardly projecting bristles. The cylinder is telescoped onto the tube while being rotated so that the bristles deflect tangentially to grip the tube.
U.S. Pat. No. 1,315,581 discloses a tool which includes a plurality of depending prongs which tend to close toward a common central vertical line and a central member which is movable along the line. Each prong is operatively connected to the member by a pivoted link. The member is adapted to be brought downward along the line to dead-center the links and thereby hold the prongs apart.
U.S. Pat. No. 4,813,732 discloses a tactile sensor based wafer which handles apparatus designed to be attached to a commercially available industrial robotic arm for manipulating semiconductor wafers with high functional reliability. The apparatus has three rod-like projections called fingers, one finger is extendable and the others are fixed. All of the fingers are instrumented with strain gauge sensors in order to allow the monitoring of all of the forces applied to the fingers during wafer handling operations. All of the sensors provide proportional data. The wafer handling apparatus enables a monitoring computer to direct the motions of a satisfactorily equipped robot arm to operate in the following modes of operation. Force controlled grasping of the wafer can be provided to insure adequate grasp for transport and to limit forces exerted on the wafer. Force monitoring while releasing a wafer can be provided to insure safe handling during transfer to another device or surface, thus, minimizing the likelihood of dropping a wafer. Proportional adaptive control of necessary robot motions can be provided to align wafers in close proximity to process carrier surfaces. Proportional adaptive control of robot motions which are necessary to guide the gripping apparatus can be provided for balanced contact with the edge of a wafer. Force monitoring can be provided for the purpose of detecting collisions with objects or humans during transport of a wafer.
U.S. Pat. No. 4,610,475 discloses a gripping apparatus for gripping and releasing objects, and for use with a micromanipulator. Spaced cantilever jaws which extend in substantially the same direction from a support are each formed of a pair of elongated ribbons of piezoelectric polymer bonded together in oppositely polarized orientation. An electrically conductive thin film is bonded to the outer surfaces of the laminate. A voltage is applied to the conductive films which causes the polymer ribbon laminates to bend toward or away from each other dependent upon the polarity of the applied voltage so that they grip an object.
Attention is also drawn to U.S. Pat. Nos. 3,491,520, 3,353,860, 3,827,437, 4,735,451, 4,590,673 and 4,955,656, U.S. Pat. No. Re. 28,663 and German OS 3136740.